Eczema, or dermatitis, is a reaction pattern that presents with variable clinical and histologic findings.
Atopic dermatitis is one aspect of atopic triad of hay fever, asthma, and eczema. It usually presents as an intermittent, chronic, severely pruritic, eczematous dermatitis with scaly erythematous patches, vesiculation, crusting, and fissuring. Lesions are most commonly on flexures, with prominent involvement of antecubital and popliteal fossae; generalized erythroderma may occur in severe cases.
Allergic Contact Dermatitis
Allergic contact dermatitis is a delayed hypersensitivity reaction that occurs after cutaneous exposure to an antigenic substance. Lesions occur at site of contact and are vesicular, weeping, crusting; linear arrangement of vesicles is common. Most frequent allergens are resin from plants of the genus Toxicodendron (poison ivy, oak, sumac), nickel, rubber, and cosmetics.
Irritant Contact Dermatitis
Irritant contact dermatitis is inflammation of the skin due to direct injury by an exogenous agent. The most common area of involvement is the hands, where dermatitis is initiated or aggravated by chronic exposure to water and detergents. Features may include skin dryness, cracking, erythema and edema.
Seborrheic dermatitis is a chronic non-infectious process characterized by erythematous patches with greasy yellowish scale. Lesions are generally on scalp, eyebrows, nasolabial folds, axillae, central chest, and posterior auricular area.